Dies for press tools



Oct. 8, 1957 v G. 5. FORD 2,803,799

DIES FORPRESS TOOLS Filed Feb. 14. 1952 mx w f6 75 4 Inventor 6 4, Mnm/ B, l' w A tlorney l are DIES FOR PRESS TOOLS Geoffrey Ewart Ford, Bedford, England, assignor to Fords (Finsbury) Limited, Bedford, England, a British com- P y Application February 14, 1952, Serial No. 271,501 Claims priority, application Great'Britain October 8, 1951 Claims. (Cl. 113-50) The present invention relates to press tools for forming articles such as bottle caps from foil strip and is more particularly concerned with dies for such press tools incorporating means for ensuring the removal of the formed article if it tends to adhere to the die.

Dies for press tools commonly employ a pressure pad upon which is mounted a pressure ring, the pad and ring being contained within a hollow cylindrical shear ring and longitudinally movable Within it against the action of a compression spring in order to eject the formed article after the forming operation.

In shearing and forming articles from metal foil, for

example, bottle caps, it is customary practice to smear the foil with a film of oil, the purpose of which is to enable the material to be drawn and shaped without tearing. Unfortunately, the use of oil for this purpose creates a tendency for the article to stick on the face of thepressure ring as the tools open and for this reason many devices have hitherto been proposed to effect positive removal of the formed article during separation of the tools.

For example, in one proposal it was suggested to draw a wire across the face of the pressure ring duringopening of the tools so as to wipe off the formed articlebefore the next succeeding shearing and'forming action of the tools. Proposals hitherto made, however, have only enjoyed a moderate success in practice because the adjustment of the parts was rather critical.

The principal object of the invention is to provide means for removing the formed article from the die of a press tool, which is eificient in operation and completely uncritical in its adjustment.

Another object is to providea die for a press tool comprising a pressure ring adapted to contact the surface of the article in a closed figure during formation but only at a small number of separate points during separation of the tools after formation of an article.

Another object is to provide a die for a press tool having a pressure ring divided into a plurality of segments with means for tilting the segments obliquely to the longitudinal axis of the die during separation of the tools after the formation of an article.

These and other objects of the invention will become more apparent in the description which is to follow.

In one convenient embodiment of the invention, one lateral end of the flange of each segment of the pressure ring is bent out of its plane in a downward directionwith respect to the axis of movement of the die so that during separation of the tools, the pressure of the spring on the flange of the pressure ring will be eccentric in its action thus to cause each segment to tilt about the bent portion as fulcrum. This tilting action ensures that contact between the pressure ring and the formed article will occur only at a specified number of points, one for each segment instead of on a complete annular surface, as heretofore. Consequently there is no adhesion of the article on the pressure ring due to the oil film, with the natural consequence that the cap is allowed to drop as soon'asthe tools are separated and there is no congestion.

Preferably the internal flange of the pressure ring is so located that one side thereof forms a surface to take the compression load of the spring guiding it in its longitudinal movement so that it cannot move laterally, therebycausing the other side of the flange to bear against the shoulder on the pressure pad.

In order that the invention may be more readily understood and appreciated, reference will now be made to the accompanying drawings which show one specific embodiment thereof by way of non-limiting example and in which;

Fig. 1 shows an axial section through the device in the normal position. a

Fig. 2 shows a plan view along the but omitting the spring, and

Fig. 3 shows a perspective view pressure ring. I

In the drawings, the shear ring 1 is of cylindrical form closed at one end by a plate 2 having an aperture through which a bolt 4 connected to the pressure padS may pass. The pressure pad 5 is in the form ofa cupshaped member, as shown, screwed to a hollow boss 6 by means of screws 7. The hollow boss 6 also accommodates the bolt 4, the construction ensuring the provision of an annular shoulder 8 projecting radially from the boss 6. Over this shoulder 8 is located a pressure ring 9 which comprises a hollow cylindrical member having an internal annular flange 10 a short distance from one end 11 thereof. This annular flange 10 is of a size to fit over the projecting annular shoulder 8 of the pressure pad 5 in such -a manner that-the shorter end-1 1 of the pressure ring beyond the flange 10 projects upwardly to form a cap for the reception of a compression spring 12 which is located within the-shear ring 1, one end pressing against theplate 2 forming the closed end wall of the shear ring and the lower end pressing on the top face of the flange 10 of the pressure ring 9. A suitable line 2-2 of Fig. l

of a segment of the nut 13 or other fixing means is associated with the bolt 4 externally of the shearring 1 to keep the whole device in secure relationship or the bolt.4 may be secured toga screwed plate located in a complete machine. Thus, in the normal position of the die thus constituted and shown in the drawings,-the pressure ring 9 will project outwardly from the shear ring 1 and be capable of longitudinal movement within the shear ring against the spring 12, as will be described later. i

The pressure ring 9 is longitudinally'divided into four segments 14 and the lateral end 15 of the flange'10 of each segment is cut along the inner wall of the segment at 16 to allow said lateral end to be bent out of-the plane of the remainder of the flange, as shown more particularly in the perspective view of the segment shown at Fig.' 3, to form in effect a cam surface for the purpose to be specified later. w

In the normal location of the die before and after forming the article which is the location shownin Fig. l, the compression spring 12 will'bear against the cam surfaces 15 of the flanges thereby-causingv each segment to tilt obliquely to the longitudinal axis of the die as shown in Fig. 1 so that instead .ofthe pressure ring 5 forming a, complete annulus .at its end whichis to come into contact with thefoil, it forms only four-contact points 17, two of whichonly are shown in Fig.1.

In operation of the-die, when the tools are-closedduring the forming'operation, the pressure ring 9 behaves exactly as a one-piece pressure ring owing to the fact that the ring, as a whole, is caused to be pressed against the forming member of the punch part of which is shown at 18 so that the contact surface of the pressure ring is a complete annulus bearing on the oil film on the foil 19 but, just before the cap is released by the tools, the resist ance of the forming member 18 is no longer available and consequently under the action of the spring 12 hearing against the cam surfaces "15 of the flanges of the -pressure ring, each segment 14 of the pressure ring tilts to bear on the formed article at only four points thus eflectively breaking the oil film on the article. Therefore it is impossible for the formed article to adhere by suction to the pressure ring through the medium of the oil film with the consequence that it may fall into a delivery chute or the like easily.

This arrangement has produced excellent results even with excessively lubricated foil which was tested for experimental purposes.

. It will be understood that the invention has been described only by way of example and that various modifications could be made to the specific details hereinbefore enumerated without in any way departing from its scope. For example, the pressure ring could be divided into three segments instead of four but, for obvious reasons, it would not be advantageous to divide the pressure ring into too many segments since this would destroy the object of the invention of havingonly a small number of contact points for the formed caps. Furthermore, the cam surfaces 15 need not be provided by cutting the flange 10 at 16. In some cases, a mere bending of the end without cutting would be sufiicient or the whole segment could be diecast or moulded to provide the surface. Al-

ternatively, the flange 10 could be made thicker than that shown in the drawings and have the cam surface machined on its upper face.

The press tool according to the invention may be used with any suitable machine, for example, with the machine according to my Patent No. 2,599,820 dated June 1952, and entitled Bottle Capping Machine.

I claim:

1. In a press tool for forming articles from metal foil of the kind comprising a punch member and a die ring which are relatively advanced together and subsequently withdrawn, a cylindrical pressure and ejector ring reciprocable within said die ring having an inwardly-directed flange spaced from its forward peripheral edge and said ejector ring being longitudinally divided into a plurality of part-cylindrical segments each with a flange portion, a support member fixed to said die ring and extending into said pressure and ejector ring and upon which said flange portions are adapted to rest when in the forward positions, a projection between each of said flange portions and the part of said member upon which it rests, said projections forming fulcra about which the said segments may tilt, and spring means acting on said segments to tilt the segments about said fulcra when the die is out of engagement with the punch.

2. In a press tool for forming articles from metal foil of the kind comprising a punch member and a die ring which are relatively advanced together and subsequently withdrawn, forming a cylindrical pressure and ejector ring reciprocable within said die ring having an inwardly directed flange spaced from its forward peripheral edge and said ejector ring being longitudinally divided into a plurality of part-cylindrical segments, each with a flange portion and with gaps between adjacent segments, a support member fixed to said die ring and extending into said pressure and ejector ring and upon which said flange portions are adapted to rest when in the forward positions, a projection on .each of said flange portions contacting the 7 said member, said projections forming fulcra about which the said segments may tilt, and spring means acting on said segments to tilt the segments about said fulcra when the die is out of engagement with the punch.

3. In a press tool for forming articles from metal foil of the kind comprising a punch member and a die ring which are relatively advanced together and subsequently withdrawn, a cylindrical pressure and ejector ring reciprocable within said die ring having an inwardly-directed flange spaced from its forward peripheral edge and said ejector ring being longitudinally divided into a plurality of part-cylindrical segments, each with a flange portion and gaps between said segments, a supporting member fixed to said die ring and extending into said presssure and ejector ring and upon which said flange portions are adapted to rest when in the forward positions, a projection between each of said flange portions and the part of said member upon which it rests, said projections forming fulcra about which the said segments may tilt, an inwardly directed flange at the rear end of said die ring, and spring means between said flange portions and said inwardly-directed flange at the rear end of said forming die ring to act on said segments and tilt them about said fulcra when the die is out of engagement with the punch.

4. In a press tool for forming articles from metal foil of the kind comprising a punch member and a die ring which are relatively advanced together and subsequently withdrawn, a pressure and ejector ring reciprocable within said die ring and comprising a cylindrical member having an internal flange spaced from the leading edge of the die ring and being longitudinally divided into a plurality of part-cylindrical segments, each having a flange portion, with gaps between adjacent segments, a supporting member fixed to said die ring and extending into said pressure and ejector ring and on which said flange portions are adapted to rest when in the forward positions,

' a cam surface on each of said flangeportions providing a fulcrum about which its segment can tilt on said supporting member, and spring means between the rear faces of said flange portions and the interior of said die ring to act on said segments and tilt them about said fulcra when the die is out of engagement with the punch.

5. In a press tool for'forming articles from metal foil of said flange portions and the interior of said die ring which are relatively advanced together andsubsequently withdrawn, a pressure and ejector ring reciprocable Within said die ring and comprising a cylindrical member having an internal flange spaced from the leading edge of the die ring and being lcngitudinallydivided into a plurality of part-cylindrical segments, each having a flange portion, with gaps between adjacent segments, a pressure pad secured to said die ring and extending into said pressure and ejector ring and having a shoulder on which the forward faces of said inwardly directed flange portions rest when in the forward positions, a cam surface on each of said flange portions comprising a portion of the flange bent out of its plane towards the said pressure pad, said cam surfaces forming fulcra about which the segments can tilt on said pressure pad, and a compression spring between the rear faces of the said flange portions and the forward face of an inwardly-directed flange of said blanking and forming ring, to act on said segments and tilt them about said fulcra when the die is out of engagement with the punch.

References Cited in the file of this patent UNITED STATES PATENTS 798,530 Rehfusss Aug. 29, 1905 2,191,836 Stromberg et al Feb. 27, 1940 2,377,351 Martin June 5, 1945 

